VB to Android

I've managed (over a very long time) to write a program in VB using Visual Studio 2008. This program is now published to my website and works well.
Probably because people shy away from downloading and running .exe files or due to lack of my understanding of search engines, I don't appear to have had much interest.
I have now decided to convert it to an Android and then, if I can manage to master Android, possibly to iOS.
Having made a start within Android Studio I am finding it very difficult and wondered if I'm missing anything.
I have a .sdf database in the original program which has fixed data and rarely needs modifcation and the data contained within it was taken from an earlier MS Access database.
I have the following two questions, which may need to eventually be independant threads, these are:

Can I use .sdf database within Android app? (I've looked at SQLite within Android but can't see how to transfer data).

Is there anything I should be aware of to help make eventual conversion to iOS any more straightforward?

Do you want to run this as a native mobile application, or as a web application? If native, then iOS and Android use very different programming languages. If web, then use standard web application tools such as html + css, javascript, jsp, php, etc. which will run on just about any web browser, including mobile ones. You can use standard web services to interrogate the device (mobile or desktop) type, browser, and such in order to scale the output to the capabilities of the device.

As I'm not sure of how to make current web download work on mobile devices, I assumed the only option was to create an app for mobiles (starting with Android). My program is probably not very professional from a programming point of view but appears to work well and the programming gets quite complicated making it difficult to convert. Is it something that, if I provided website address, I could get looked at and then given advice on best way to proceed or is this outside of scope of this forum?

Centorpe, you current have Windows Form like app.exe, built with VB.NET right? That app.exe can only run at windows with .NET Framework installed. It would probably run at Windows Mobile, but I'm not sure about the new Windows Phone, I think only WPF(Windows Presentation Foundation) apps run there.

Anyway, if you want to make your app accessible for most people you have basically 3 options:

Program a version for each plataform (Windows, Mac, Android, IOS, Linux and etc)

Use meta developomet softwares that genereate codes or executable for various plataforms (I never liked this option, there're lots of plataforms like that but I never used one that worked well for complex apps).

Build an Web App that run in any modern browser.

Option 3 for me it's the best. You create only one app that'll run in allmost any modern browser.

The point is, a web app it's very different from a Windows Form or a Android app. Those two are client apps. With web, you have the server and the client.
So, you could use part of your VB.NET code to create the server side of your web app. But you'll have to create a new interface with HTML, CSS and JavaScript.

You also must bear in mind that in a browser you won't have the same access to the client's machine that you would have with native apps.

If it seems a good option for you, just google VB.NET Web application to get started with it.